Tube cutter



FIG. 1 is a front-right side perspective view of the tube cutter of my new design;

FIG. 2 is a rear-left side perspective view thereof;

FIG. 3 is an enlarged top perspective view thereof; and,

FIG. 4 is an enlarged bottom perspective view thereof.

The portions of the tube cutter shown in broken lines form no part of the claimed design. 

The ornamental design for a tube cutter, as shown and described. 